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Graphite Engineering Material Review

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Graphite is a very good engineering material for high temperature, high-pressure transfer of liquids, gases, steam, chemicals and corrosives. It can be manufactured from high purity, high and thermal treatment to produce expanded graphite crystals. The expanded graphite crystals are then formed into foils, sheets and other shapes through various processes.

Graphite has a layered, planar structure. In each layer, the carbon atoms are arranged in a hexagonal lattice with separation of 0.142 nm, and the distance between planes is 0.335 nm. The two known forms of graphite, alpha (hexagonal) and beta (rhombohedral), have very similar physical properties (except that the graphene layers stack slightly differently). The hexagonal graphite may be either flat or buckled. The alpha form can be converted to the beta form through mechanical treatment and the beta form reverts to the alpha form when it is heated above 1300 °C. The layering contributes to its lower density

Graphite Classifications:

• Natural Graphite
  • Amorphous
  • Flake
  • High Crystalline
  • Synthetic

Property	Typical
Bulk Density (g/cm3)	1.3-1.95
Porosity (%)	0.7-53
Modulus of Elasticity (GPa)	8-15
Compressive strength (MPa)	20-200
Flexural strength (MPa)	6.9-100
Coefficient of Thermal Expansion (x10-6 °C)	1.2-8.2
Thermal conductivity (W/m-K)	25-470
Specific heat capacity (J/kg-K)	710-830
Electrical resistivity (ohms-m)	5x10-6 - 30x10-6

Graphite is readily available as follows:

• Film or flexible stock
• Sheet stock
• Rounds and other similar shapes
• Reinforced or other composite formulations
• Iron mill scale sheet
• High purity stock shapes
• Electrical conductivity applications
• Laminates

Applications

• Brake linings or friction material
• Foundry facings and lubricants
• Electrodes for welding applications
• Powder and scrap
• Gaskets material for automotive, petroleum and chemical, paper, and nuclear industries.
• Thermal barrier at high temperature to provide outstanding reflectivity.
• Fuel cell industry for bipolar plates.
• Sealing high temperature valves, shafts and flanges.
• Barrier, linings or protective layer for vessels containing hot or corrosive fluids.